断続切削時の工具切れ刃摩耗と欠損発生の解析的予測

Abstract

A characteristic equation of carbide tool wear in interrupted turning operation is derived and verified experimentally to hold well by measuring the distributions of wear, stress and temperature on rake face at the steady state. A computer simulation of crater wear development is then carried out by applying the wear equation, of which the characteristic constants are obtained from a single wear test. The change of cutting stress distributions on rake face at the engagement with the crater wear development is obtained experimentally. The crater wear does not any effect on the variation of cutting forces during the engagement but on the distributions of cutting stress at the instant of impact. A tool-chip contact length is limited within an area between the cutting edge and the front edge of crater at the moment of impact. For the arbitrary wear development, the transient variation of impact stress field within cutting edge during the edge engagement in interrupted turning is obtained though FEM calculation using the stress distribution obtained above. In collation of the most dangerous state of the transient stress with the fracture criterion at each element for the arbitrary wear state, both the variation of fracture probability distribution with number of interruption and the wear development with cutting distance can be also predicted.